Phasable ganged potentiometer



Jan. 10, 1961 EL M S 51 All (0,

INVENTOR.

16554,? luup,

United States Patent F PHASABLE GANGED POTENTIQMETER Elias Blanca, LosAngeles, Calif assignmto Daystrom, Incorporated, Murray Hill, N.J., acorporation of New Jer y Filed Aug. 4, 195,8, Ser. No. 752,912.

13. Claims,- (Cl. 338-135) The present invention relates generally tovariable resistors or potentiometers, and is more particularly concernedwith devices of this type which may be built inminiature or extremelysmall size units, and which may be utilized singly or ganged together.

Heretofore, potentiometer units have been ganged by securing the casingstogether by means of clamping rings which would permit individual unitsto be phased by shifting of the respective casings. This necessitated aloosening of the ganged assembly and necessitated a readjustment of thephasing of each unit and a recheck before the clamping rings were againtightened. The conventional constructions were very inconvenient andhard to adjust. Moreover since the terminals for each casing were infixed relation to the casing, shifting of the casings during phasingalso resulted in a shifting of the terminals. It was therefore difficult.to use a pro-assembled wiring harness with the conventionalarrangements.

Having in mind the inherent disadvantages of conventional constructions,it is a primary object of the present invention to provide a novelpotentiometer unit which is so arranged that the casings may be securedin rigid relation, thus permitting the use of pre-assembled wiringharness, and wherein the units may be independently phased from theexterior of their respective casings.

it is a further object to provide in a potentiometer of the characterdescribed, an adjustable wiper contact which can be adjusted after thecasings are assembled, thus making it unnecessary to have to calculatethe wiper position prior to assembly.

Still another object is to provide a novel potentiometer construction,wherein the wiper contact is phasable through 360.

Still another object is to provide improved means for securing thepotentiometer units in ganged relation in such a way as to result inless weight than gang potentio meters utilizing the heretofore knownarrangements.

Further objects of the invention will be brought out in the followingpart of the specification, wherein detailed description is for thepurpose of fully disclosing the invention without placing limitationsthereon.

Referring to the accompanying drawings, which are for illustrativepurposes only:

Fig. 1 is a perspective view of a ganged potentiometer embodying aplurality of potentiometer units constructed according to the presentinvention.

Fig. 2'is a longitudinal sectional view of an assembly embodying asingle potentiometer unit;

Fig. 3 is a transverse sectional view taken substantially on line 33 ofFig. 2, portions being cut away to show the cooperative relationship ofvarious parts of the device;

2,968,015 Patented Jan. 10, 1961 Fig. 4 is an enlarged fragmentaryelevational view of the casing access opening seal, as viewedsubstantially in the direction of the arrow 4 of Fig. 3; and

Fig. 5 is a fragmentary sectional view illustrating the manner in whicha plurality of potentiometers maybe secured together in ganged relationwith their casings in end-to-end relation, according to the presentinvention.

Referring more specifically to Fig. 1 of the drawings, for illustrativepurposes, a plurality of potentiometer units constructed in accordancewith the present invention, as generally indicated at A, are shown asbeing secured together in end-to-end relation to form a ganged assemblyoperable by an actuating shaft 1t Referring primarily to Fig. 2, theconstruction of a single potentiometer unit will first be described. Asshown in Fig. 2, the potentiometer unit comprises a main casing 1 ofmolded or otherwise formed plastic or other suitable material to providea circular cup-like member which is open at one end and at the oppositeend is formed with an inturned fian e 12, the inner periphery of whichbounds a restricted end opening 13.

The shaft lit is rotatably supported in end caps 14 and i5 respectivelywhich are secured to the opposite ends of the casing 11. The end cap 14may be fabricated to accommodate the potentiometer for different typesof mountings. For example, the end cap, 14 may be constructed for panelmounting. As shown herein, the cap provides a servo mounting, and is ofgenerally ring-shaped configuration, being centrally formed with atubular bearing support 16. The shaft in is rotatably supported in thisend cap by antifriction bearing 17 having an outer race 18 which issecured and retained in the bearing support by a retaining ring 19,while the inner race 2%} is secured to the shaft between a pair of snaprings 21 and 22, a spring washer 23 being interposed between one ofthese rings and the inner race of the antifriction bearing.

The end cap 14 is secured to the casing 111 at peripherially spacedpoints by means of a stud 24- which has its outer end threadedly engagedwith the end cap, while the other end projects through an opening 25 ofthe casing 11 into a recess 26 where it threadedly engages one end of athreaded sleeve 27.

As will be seen in Fig. 2, the end cap 15 is centrally formed with aninternal recess 28 within which antifriction bearing 29 is retained, theinner race 30 of this bearing being in engagement with the adjacent endof the shaft It), while the outer race 31 of the bearing is retained inthe recess of the cap. The cap 15 is secured to the open end of thecasing 11 by means of headed studs 32 which are adapted to extendthrough an opening in the cap 15 arranged to align with recess 26. Thethreaded end of the stud 32 threadedly engages into the adjacent end ofthe threaded sleeve 27. By tightening the studs 32, the cap 15 will betightly engaged with the adjacent edge of the casing 11. With theforegoing arrangement, the potentiometer components within the casing 11are enclosed and protected.

The potentiometer components include a resistance element 34 and anassociated wiper contact 35. The resistance element is seated in anannular groove or recess 36 on the inner surface of the flange 12, andcomprises a plurality of spiralled turns of resistance wire 37 which iswound over a supporting ring-like core member 38, suit- .able insulation39 being interposed between the wire turns the core ends, so that thecore structure may expand and contract under temperature changes.

The wiper contact is carried by the shaft and is assembled into atwo-part supporting structure permitting movement of the wiper contactdirectly in response to shaft movements, and independent adjustment ofthe wiper contact in order to permit phasing or a change of relativeposition between the resistance element and wiper contact for a givenshaft position. More specifically, the two-part supporting structureincludes a first part 41 fabricated from a suitable plastic or othermaterial to provide a circumferentially extending radially projectingflange portion 42 and an integrally formed hub portion 43 whichsurrounds the shaft 10 and is fixedly secured thereto as by a set screw44. One side of the flange 42 is formed with an annular groove 45 forreceiving one end of the second part 46 of the mounting structure forthe wiper contact. The second part is generally ring-shaped and isrotatably mounted on the hub portion of the first part. The second parthas an end 47, the end which is positioned in the groove 45, fabricatedto form a ring gear with teeth 48 formed on its outer periphery. Theother end of the second part 46 is formed with an outwardly projectingcircumferentially extending flange 49 which is adapted to bear againstthe adjacent face of flange 42 so as to axially locate the end 47 withinthe groove 45.

As shown best in Fig. 3, the wiper contact 35 is constructed as anintegral radially extending projection from a ring-shaped body portion50 which surrounds the shaft and is positioned in face engagement on oneside with the end surface of the flange 49. This assembly is retained inposition and preloaded by means of a snap ring 51, and a spring washer52 which bears against a metal Washer 53, an insulating spacer ring 54being interposed between the washer 53 and the body portion 50 of thewiper contact element. In order to prevent relative circumferentialmovement of the wiper contact with respect to the second part 46 of thesupport structure, the surface of the second part which is in engagementwith the body portion 50 of the wiper contact is provided with a socket55 into which there extends a keyfinger 56 formed as a part of the wipercontact, thus locking the parts against relative circumferentialmovement.

Means are provided for relatively moving the first and second parts in acircumferential direction, and locking these parts in the adjustedposition. This is accomplished by mounting a worm 57 in the flange 42,this worm being in meshed relation with the teeth 48 of the second part46. The worm 57 is rotatably mounted in a drilled or otherwise formedpassage 58 which has an open end 59 in the peripheral edge of the flange42. The worm is longitudinally retained in the passage 58 by means of akeeper and groove interconnection as generally indicated by the numeral60. The outer end of the worm member is shown as being provided with asocket 61 for receiving the end of a suitable tool by which the worm maybe rotated, as will be more fully explained subsequently.

In order to permit the actuation of the worm 57 and the adjustment ofthe wiper contact, after the potentiometer is fully assembled andwithout having to disassemble the casing, the outer wall of the casing11 is provided with a passage 62 which is directionally positioned insuch a manner that the passage 58 may be brought into axial alignmenttherewith by turning the shaft 10 to proper position.

The outermost end of the passage 62 has an enlarged cylindrical portion63 which is axially positioned in eccentric relation to the axis ofpassage 62. A sealing plug 64 is retained in rotatable seated positionin the portion 63 by a groove and keeper as generally indicated at 65.The plug 64 has an off-center opening 66 which may be brought into andout of registration with the axis of passage 62 by inserting a smalltool such as a screw driver into a receiving slot 67 in the outer end ofthe plug. By rotating the off-center opening into registration with theaxis of the passage 62, a tool may be inserted into the socket 61 formoving the wiper contact to phase the potentiometer. After theadjustment is completed, the casing may then be sealednby the simpleexpedient of rotating the opening 66 to a position wherein the outer endof the passage 62 will be closed.

Connection terminals 68, 69 and 70 are supported in the outer wall ofcasing 11, as primarily shown in Fig. 3. These terminals are connectedwith the components of the potentiometer through permanently positionedeyelets 71, 72 and 73, each of the terminals being connected to aneyelet by means of a connector strip 74. As shown, the eyelets 71 and 72are respectively connected to the ends of the resistance element, whilethe eyelet 73 connects with an eyelet 75, through a conductor 76. Theeyelet 75 is utilized to secure a brush contact structure 77 in fixedposition on the flange 12. The brush contact has oppositely extendingspring arms 78' and 78" adapted to bear against and form a slidingcontact with the adjacent surface of the body portion 50 of the wipercontact structure. With the arrangement described above, it will beappreciated that the wiper contact may be rotated by rotating the shaft10 through a complete circle of 360, and that also by actuating the wormand gear, phasing of the wiper contact may likewise be accomplishedthrough a complete circle of 360. Moreover, by utilizing a worm and geararrangement for phasing, the wiper contact may be set at any position,and when so adjusted is locked against shifting movement by the inherentcharacteristics of the worm and gear drive.

One of the desirable features resulting from the potentiometerconstruction described above resides in the fact that the casing 11 maybe constructed of shorter length than with conventional arrangements,and that a plurality of potentiometer units in their respective casings11 may be secured in end-to-end axial alignment to produce a gangedassembly in which the respective wiper contacts may be phased afterassembly by simply moving the shaft 10 to bring the actuating worms intoproper position for adjustment through the passage 62 of eachpotentiometer casing.

The manner in which the casings 11 are interconnected is more or lessschematically illustrated in Fig. 5, wherein two casings 11a and 11b aresecured in ganged assembly. It will be appreciated, however, that thegang may include additional casings as desired, and Fig. 1 shows threecasings ganged into a single unit.

For interconnecting additional casings, a straight stud 79 is usedinstead of a headed stud such as shown at 32. The outer end of the stud79 connects with one end of the threaded sleeve 27 of the casing whichis being added. To connect the end cap 15, a stud 32 is utilized in thesame manner as previously described and shown in Fig. 2.

A great advantage in being able to phase the potentiometers after thecasings are in assembled relation resides in the fact that the phasingmay be accomplished with my construction without disturbing the positionof the terminals, thus permitting the use of a pre-assembled wiringharness.

Various modifications may suggest themselves to those skilled in the artwithout departing from the spirit of my invention, and, hence, I do notwish to be restricted to the specific form shown or uses mentionedexcept to the extent indicated in the appended claims.

I claim:

1. A potentiometer, comprising: a casing; a ringshaped resistanceelement in said casing; a rotatable shaft extending axially of saidresistance element and projecting from said casing; a slider contactcarried by said shaft and movable thereby over said resistance element;and means for varying the angular position of said slider contactwithrespect to said shaft, said means including a rotatable member having anaxis of rotation at right angles to said shaft axis and being accessiblefor rotationfrom the casing exterior.

2. A potentiometer, comprising: a casing; a ringshaped resistanceelement in said casing; a rotatable shaft n said casing extendingaxially of said resistance element; a two-part support carried by saidshaft including a first part affixed to the shaft for rotationtherewith, and a second part movably supported on said first part forangularly variable positions of adjustment about the shaft axis; aslider contact carried by said second part movable over said resistanceelement; and a worm and gear interconnection between said parts operableto relatively vary their angular relationship with respect to the axisof said shaft, said interconnection being accessible for actuationthrough an opening in said casing.

3. A gang potentiometer, comprising: a plurality of potentiometer unitssecured in axial alignment within a casing structure, each of said unitsincluding a ringshaped resistance element concentrically disposed abouta common actuating member; a wiper contact carried by said member; andmeans for circumferentially varying the angular position of the wipercontact with respect to said member, said means in each case beingaccessible from the casing exterior through an opening therein.

4. A gang potentiometer, comprising: a plurality of potentiometer unitsin axial alignment with their casings fixedly interconnected inend-to-end stacked relation; a rotatably supported shaft extendingaxially of said interconnected casings; a ring-shaped resistance elementin each of said casings; a wiper contact in each of said casings carriedby said shaft and movable thereby along said resistance element;exterior connection terminals carried by each casing having electricalconnection with the resistance element and wiper contact therein; andmeans in each potentiometer unit for independently phasing said contacttherein, while maintaining said axial alignment and the relativepositions of the terminals of the units.

5. A gang potentiometer, comprising: a plurality of potentiometer unitsin axial alignment with their casings fixedly interconnected inend-to-end relation; a rotatably supported shaft extending axially ofsaid interconnected casings; a ring-shaped resistance element in each ofsaid casings; a wiper contact in each of said casings carried by saidshaft and movable thereby along said resistance element; exteriorconnection terminals carried by each casing having electrical connectionwith the resistance element and wiper contact therein, said contacts ofthe respective potentiometer units being relatively fixedly positioned;and means accessible from the exterior of said casings for relativelyphasing the wiper contacts of said potentiometer units, whilemaintaining said casings fixedly interconnected.

6. A gang potentiometer, comprising: a plurality of potentiometer unitsin axial alignment with their casings fixedly interconnected inend-to-end relation; a rotatably supported shaft extending axially ofsaid interconnected casings; a ring-shaped resistance element in each ofsaid casings; a wiper contact in each of said casings carried by saidshaft and movable thereby along said resistance elements; exteriorconnection terminals carried by each casing having electricalconnections with the resistance elements and wiper contact; means ineach potentiometer casing for phasing the wiper contact thereinincluding a rotatable member operable by. a tool insertable through acasing opening; and means for closing said opening.

7. A gang potentiometer, comprising: a plurality of potentiometer unitssecured in axial alignment, each of said units including a resistanceelement and a wiper contact, a common actuator for said units, and meansaccessible from the exterior of each of said units for independentlyvarying the relationship between said wiper contact and associatedresistance element, to vary the phase relationship between therespective units, while maintaining said units in their initialassembled ganged relationship. 0

8. A potentiometer, comprising: a casing; an elongate ring-shapedresistance element in said casing; rotatable wiper means having contactwith said resistance element; rotatable actuating means for moving saidwiper means to vary its contact position with said resistance element inaccordance with movements of said actuating means, said actuating meansand said wiper means having coincident axes of rotation; and manuallyoperable adjusting means for independently varying the relative positionof said wiper means with respect to said resistance element, whilemaintaining a fixed relationship between said actuating means and saidcasing, said adjusting means being operable to move the wiper meanscircumferentially of said axes through an angle of 360.

9. A potentiometer, comprising: an elongate ringshaped resistanceelement; a wiper contact member adjustably movable from one end to theother of said resistance element; first means for moving said contactmember including an actuating member normally movable to adjust theposition of said contact member between the ends of said resistanceelement in accordance with changes in position of the actuating member;and manually operable second means interconnecting said actuating memberand said contact member adjustable to vary the position of said contactmember from one end to the other of said resistance element, whilemaintaining the actuating member fixed, whereby the angular relationshfpbetween the actuating member and the contact member may be changed atwill.

10. A potentiometer, comprising: a casing; a ringshaped resistanceelement in said casing; a rotatable shaft extending axially of saidresistance element and said casing; a slider contact carried by saidshaft and rotatable thereby over said resistance element; and phaseadjusting means for varying the angular position of said slider contactcircumferentially with respect to the axis of said shaft, said phaseadjusting means being accessible from the exterior of said casing forchange under operating conditions.

11. A potentiometer, comprising: a casing; a ringshaped resistanceelement in said casing; a rotatable shaft extending axially of saidresistance element and said casing; a slider contact carried by saidshaft and movable thereby over said resistance element through an angleof 360; and means for mounting said slider contact on said shaft forrotation therewith including parts cooperable to independently vary theangular position of said slider contact circumferentially with respectto the axis of said shaft through an angle of 360.

12. A potentiometer, comprising: a ring-shaped resistance element; arotatable shaft extending axially of said resistance element; a two-partsupport carried by said shaft, one of said parts being aflixed to saidshaft for rotation therewith, and the other of said parts being movablysupported on said one of said parts for angularly variable positions ofadjustment about the shaft axis; a slider contact carried by said otherof said parts and being movable over said resistance element about anaxis of rotation coincident with said shaft axis; and manually operableadjusting means for moving said other of said parts through 360 withrespect to said one of said parts to vary its angular position withrespect to said shaft and the position of said contact on saidresistance element.

13. A potentiometer, comprising: a ring-shaped resistance element; arotatable shaft extending axially of said resistance element; a two-partsupport carried by said shaft including a first part affixed to theshaft for rotating therewith, and a second part movably supported onsaid first part for angularly variable positions of ad justment aboutthe shaft axis; a slider contact carried by said second part movableover said resistance element about an axis of rotation coincident withsaid shaft axis; and means for relatively rotating said first part andsaid second part to circumferentially vary its angular position withrespect to said shaft and the position of said contact on saidresistance element, including a worm and gear interconnection betweensaid parts which coact to interlock said parts against relative movementwhen the parts are rotated as a unit by the shaft.

References Cited in the file of this patent UNITED STATES PATENTS IPieper July 20, 1891 Stout Oct. 12, 1943 Canziani et al. Apr. 8, 1952Barclay Oct. 27, 1953 Mucher Apr. 20, 1954

